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Wang helps NASA advance sonic boom research

Lily Wang

Research by Lily Wang, associate professor of architectural engineering, was featured Oct. 18 on ScienceDaily.

Funded by NASA, Wang’s work with graduate student Christopher Ainley explored how noise bursts affect the performance and perceptions of test subjects. The UNL team worked to “find a threshold value under which the noise would not significantly affect” the research subjects, who were studied while they concentrated on math problems.

The research helped NASA advance its low-boom supersonic aircraft program, and mitigate sonic booms — cones of compressed air in the wake of aircraft traveling faster than the speed of sound that generate noise deemed loud and potentially unnerving.

Durham School researchers tested bursts of approximately 50 to 80 dBA (decibel units measured with a filter used to approximate the human ear's response to sound), with sounds at the lower level comparable to street noise and, at higher numbers, near the sound level of an operating vacuum cleaner.

While the test subjects solved a lower percentage of problems correctly when interrupted with a noise at the louder end of the spectrum, the difference was not enough to be statistically significant, Science Daily reported. However, there was a significant difference in the levels of annoyance that the participants reported when quizzed afterward about their perceptions of the noise environment.

"The test subjects sort of adjusted to the quieter booms, but the louder ones remained jolting," said Wang. "This suggests that the acceptable noise from sonic booms should not be higher than 70 dBA once it gets inside the house."